As part of the deal, Poland would receive American F-16 fighters to make up the loss.
The plan would help Ukrainians by providing them with more aircraft but it also increases the risk of the war.
What are the Polish fighter jets?
The Mikoyan MiG-29 (Fulcrum) is a lightweight, twin-engine jet fighter aircraft designed in the former Soviet Union.
Developed in the 1970s, they were used to counter US fighter jets and first entered service with the Soviet Air Force in the early 1980s.
They were originally created for combat but have since been redesigned to become agile fighters for multiple purposes and capable of limited ground attack.
Later models have glass bubble canopy cockpits, modern radar, infrared search and track sensors and some can be refuelled from the air.
It has been used by a number of countries outside Russia including Algeria, Iran and Syria.
Why did US dismiss plans?
NATO has said it does not want direct conflict with Russia.
Russia’s defence ministry warned any countries offering air fields to Ukraine for attacks may be considered as having joined the war.
The Pentagon has said if the Polish deal to deliver planes to the US Ramstein air base in Germany was taken up it would raise “serious concerns for the entire NATO alliance”.
US President Joe Biden has ruled out sending troops into Ukraine to fight - which also applies to fighter pilots.
Pentagon spokesman John Kirby said: “It is simply not clear to us that there is a substantive rationale for it.
"We will continue to consult with Poland and our other NATO allies about this issue and the difficult logistical challenges it presents, but we do not believe Poland’s proposal is a tenable one.”
What have Poland and Ukraine said?
Over the weekend, Ukrainian President Volodymyr Zelensky made a "desperate plea" to US Congress members for further military aid including planes.
He also issued a plea to European countries to provide Russian-made planes to help it defend the nation from the invasion.
Polish Prime Minister Mateusz Morawiecki said his country is "not ready to make any moves on our own" because "we are not party to this war".
He added: "Any decision of delivering offensive weapons has to be taken by the entire NATO on a unanimous basis.”
How many fighter jets does Poland have?
The Polish Air Force currently fields 27 MiG-29s, according to military information source Janes World Air Forces.
Although, only 23 of these fighter jets are reported to be active by FlightGlobal.com.
Other European nations using these aircraft are Bulgaria which is estimated to have 14 and Slovakia thought to have 11.
The Ukrainian Air Force inherited Soviet-era combat aircraft in 1991.
It still operates them now, including the MiG-29 Fulcrum, so their pilots are trained to use these planes.
A message from the editor:
Thank you for reading. NationalWorld is a new national news brand, produced by a team of journalists, editors, video producers and designers who live and work across the UK. Find out more about who’s who in the team, and our editorial values. We want to start a community among our readers, so please follow us on Facebook, Twitter and Instagram, and keep the conversation going. You can also sign up to our newsletters and get a curated selection of our best reads to your inbox every day.